1. Field
One or more embodiments described herein relate to a nonvolatile memory device, program method, and program verification method.
2. Description of the Related Art
A semiconductor memory is fabricated from one or more semiconductor materials including silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), or the like.
Semiconductor memory devices include volatile memory devices and a nonvolatile memory device. One kind of nonvolatile memory device known as a flash memory device is used in various fields because of its fast operating speed, low power, low noise, and high capacity characteristics. A flash memory device may program data using an incremental step pulse programming (ISPP) scheme. In this scheme, data is programmed by performing a plurality of program loops. Each program loop may include a program step in which a program pulse is applied to a word line and a verification step in which states of memory cells are verified.
In the verification step, program pass or program failure is determined according to the result of counting failure bits (e.g., memory cells not programmed to a target program state). A next program loop is performed according to the result of this determination. The time to perform a failure bit counting operation may be longer than the time to perform the program step or a verification read operation. Thus, execution of a next program loop may be delayed due to a long counting operation. This decreases total program speed.